U.S. President Barack Obama has ordered 350 more military personnel to Iraq.

The White House made the announcement in a statement late on September 2, saying additional troops were being sent to "protect our diplomatic facilities and personnel in Iraq as we continue to support the government of Iraq in its fight" against Islamic State militants.

The statement also noted, "These additional forces will not serve in a combat role" and would be deployed in Baghdad.

The statement said top U.S. officials, including U.S. Secretary of State John Kerry and Defense Secretary Chuck Hagel, would soon travel separately to the Middle East to "build a stronger regional partnership" against the militant group known as Islamic State (IS).

The announcement comes as the militants claimed they had executed another U.S. journalist, Steven Sotloff, in Syria.

The militants released a video purportedly showing the murder of the 31-year-old journalist, with a militant in the video vowing to next kill David Haines, believed to be a British aid worker.

The militant gave a warning to other governments not to join an "evil alliance with America."

The militant in the latest video is believed to be the same person who was in an earlier video showing the beheading of U.S. journalist James Foley.

That militant, whose face is almost entirely hidden, speaks in English with a British accent, leading investigators to believe he is a British national who went to Syria to join militants there fighting against the government of Syrian President Bashar al-Assad.

Meanwhile, U.S. air strikes on September 2 targeted IS militants near the Mosul Dam in northern Iraq.

The U.S. Central Command said in a statement the air strikes had destroyed 16 vehicles near the dam.

Islamic State militants have been accused of committing a wide range of atrocities.

The group has executed thousands of non-Sunni Muslims, members of other religions, Syrian, and Iraqi government troops and foreigners.

IS is also accused of abducting women and girls and abusing them.

Rights groups say IS is responsible for committing war crimes and genocide in areas of Syria and Iraq under their control.